Constraint

CONSTRAINT, noun Irresistible force, or its effect; any force, or power, physical or moral, which compels to act or to forbear action, or which urges so strongly as to produce its effect upon the body or mind; compulsion; restraint; confinement.

Not by constraint but by my choice, I came.

Feed the flock of God, taking the oversight thereof, not by constraint but willingly. 1 Peter 5:2.